Composite sleeve for ladle stopper rods



Juiy 22, 1969 s. E. WEED coMPosrTE SLEEVE Eon LADLE sToPPER nousoriginal Filed March 12, 1965 Seth E Weed United States Patent OCOMPOSITE SLEEVE FOR LADLE STOPPER RODS Seth E. Weed, Penn HillsTownship, Pa., assignor to Vesuvius Crucible Company, Swissvale, Pa., acorporation of Pennsylvania 'Continuation of application Ser. No.439,323, Mar. 12,

1965. This application May 26, 1967, Ser. No. 641,538 Int. Cl. C21b7/12; F161 9/14, 57/00 U.S. Cl. 13S-140 6 Claims ABSTRACT F THEDISCLOSURE A sleeve for protecting a metal stopper rod comprising arefractory unitary hollow cylinder having an outer stratum and an innerstratum, the material of the outer stratum having a greater resistanceto corrosion and erosion than the material of the inner stratum and thematerial of the inner stratum having a greater thermal insulating effectthan the material of the outer stratum. The wall thickness of the innerstratum is substantially greater than, preferably at least double, thewall thickness of the outer stratum. The inner stratum may be ofzirconia, bubble alumina or refractory clay, and the outer stratum maybe of alumina, magnesia, a mixture of refractory clay and graphite,Zircon or spinel.

This application is a continuation of my copending application Ser. No.439,323, filed Mar. 12, 1965, now abandoned.

This invention relates to a composite sleeve for ladle stopper rods. Itrelates more particularly to a sleeve affording both optimum corrosionand/or erosion resistance and optimum thermal insulation.

Metal stopper rods, normally made of steel, are used for operating ladleStoppers of the type employed in bottom pour ladles which are used forreceiving molten steel tapped from open hearth or other steel makingfurnaces and teeming the molten steel into ingot molds. The steel rod isdisposed in the molten steel whose temperature may be of the order of2900-2950 F. for a period 0f thirty to sixty minutes. The hightemperature of the molten steel would soften or melt the rod if the rodwere not insulated against such temperature. But the slag which isunavoidably formed in steel making and which is tapped from the steelmaking furnace along with the molten steel or which forms on the surfaceof the molten steel in the ladle may be highly corrosive and/ or erosivetending to deteriorate insulating material used to protect the steel rodfrom the heat of the molten steel.

The use of sleeves disposed about steel ladle stopper rods is universal.However, a sleeve made of material which is readily attacked by thecorrosive or erosive slag does not give satisfactory results, and thesame is true of a sleeve which does not afford adequate heat insulationto the rod.

I provide a sleeve for protecting a metal stopper rod which comprises aunitary hollow cylinder having an outer stratum of corrosionand/orerosion-resistant refractory material and an inner stratum of thermalinsulating refractory material. My sleeve thus affords optimum thermalinsulation for the rod while at the same time satisfactorily resistingthe corrosive and/or erosive action of the slag.

The relative wall thickness of the inner and outer strata may varydepending upon conditions. Normally the wall thickness of the innerstratum of thermal insulating refractory material should besubstantially greater than the wall thickness of the outer stratum ofcorrosionand/or erosion-resistant refractory material; in a preferredform the wall thickness of the inner stratum is 3,456,690 Patented July22, 1969 as least double the wall thickness of the outer stratum. Theremay, however, be special cases in which the wall thickness of the outerstratum may equal or even exceed the wall thickness of the innerstratum. The corrosionand/ or erosion-resistant material may be selectedto counteract the action of a particular slag. If a highly corrosiveslag is to be dealt with the refractory material may be selected for itsresistance to corrosion while if a highly erosive slag is to be dealtwith the refractory material may be selected for its resistance toerosion. In certain cases the material may be one having both optimumresistance to corrosion and optimum resistance to erosion or it may haveproperties such that it would be selected as a compromise between amaterial having optimum resistance to corrosion and one having optimumresistance to erosion.

The inner stratum is of refractory material having relatively greatthermal insulating capacity while the outer stratum is of refractorymaterial having relatively great corrosion and/or erosion resistance. Ina preferred form the inner stratum may be of at least one materialselected from the group consisting of zirconia, bubble alumina andrefractory clay while the outer stratum may lbe of at least one materialselected from the group consisting of alumina, magnesia, a mixture ofrefractory clay and graphite, Zircon and spinel. In another preferredform the inner stratum may be of at least one material selected from thegroup consisting of bubble alumina and refractory clay while the outerstratum may be of at least one material selected from the groupconsisting of zirconia, alumina, magnesia, a mixture of refractory clayand graphite, Zircon and spinel.

Preferably the ends of the outer stratum are in the same transverseplanes as the ends of the radially outer portion of the inner stratumand the sleeve has at one end an externally tapered endwise projectionand at the other end a recess complementary in shape to the projectionto receive a like projection of an identical sleeve.

More specifically, the sleeve may comprise an inner hollow cylindricalstratum of thermal insulating refractory material having at one end anexternally tapered endwise projection at the radially inner portionthereof and at the other end a recess complementary in shape to theprojection to receive a like projection of an identical sleeve and anouter hollow cylindrical stratum of corrosionand/ or erosion-resistantrefractory material disposed about the inner hollow cylindrical stratumin close embracement therewith with its ends in the same transverseplanes as the ends of the radially outer portion of the inner hollowcylindrical stratum.

The sleeve may be made by providing a hollow cylinder of corrosionand/or erosion-resistant refractory material, inserting thereinto a pugof formable thermal insulating refractory material and forcing a formingmau- `drel axially through said pug to form Ia hollow cylindrical innerstratum of the thermal insulating refractory material Within the hollowcylinder of corrosion and/or erosion-resistant refractory material. Asabove indicated, desirably there is formed at one end of the sleeve anexternally tapered endwise projection and at the other end of the sleevea recess complementary in shape to the projection to receive a likeprojection of an identical sleeve.

Alternatively the sleeve may be made by inserting into a generallycylindrical mold a first pug of formable corrosion and/orerosion-resistant refractory material, forcing a forming mandrel axiallythrough the first pug to form a hollow cylindrical outer stratum of thecorrosion and/or erosion-resistant refractory material, insertingthereinto a second pug of formable thermal insulating refractorymaterial and forcing a forming mandrel axially through the second pug toform a hollow cylindrical inner stratum of the thermal insulatingrefractory material within the hollow cylindrical outer stratum ofcorrosion and/ or erosion-resistant refractory material.

The tapered endwise projection and complementary recess may be formedentirely in the material of the inner stratum, particularly when thewall thickness of the inner stratum is greater than the wall thicknessof the outer stratum.

The sleeve may be made by various other processes known to those skilledin the art, for example, by appropriate selection and combination ofpressing, extruding, casting, ramming, jiggering or other steps. Theinner and outer strata may be separately preformed and the inner stratummay be pressed into the outer stratum with suitable cement or otheradhesive between the strata to cause them to permanently adhere to eachother. The separately formed strata may be thus assembled either when inthe green state or after having been fired.

Other details, objects and advantages of the invention will becomeapparent as the following description of a present preferred embodimentthereof proceeds.

In the accompanying drawings I have shown a present preferred embodimentof the invention in which:

FIGURE 1 is an axial cross-sectional view through a composite sleeve forladle stopper rods embodying my invention, and

FIGURES 2-5 are reduced scale diagrams illustrating successive steps inone method of forming the sleeve.

Referring first to FIGURE l, the sleeve is designated generally byreference numeral 2 and comprises an inner stratum 3 of thermalinsulating refractory material which purely by way of example may bedeemed to be refractory clay .and an outer stratum 4 of corrosionand/orerosion-resistant refractory material which purely by way of example maybe deemed to be a mixture of refractory clay and graphite. As shown inFIGURE l the wall thickness of the inner stratum 3 is substantiallygreater than the wall thickness of the outer stratum 4 and indeed is atleast double the wall thickness of the outer stratum 4.

The sleeve has at one end (the upper end viewing FIGURE l) an externallytapered endwise projection 5 and at the other end (the lower end viewingFIGURE l) a recess 6 complementary in shape to the projection 5 toreceive a like projection of an identical sleeve. In the form shown theprojection 5 and recess `6 are both formed entirely in the inner stratum3 because of the relatively great wall thickness of the inner stratum.In other cases the projection and recess may be formed partly in theinner stratum and partly in the outer stratum. As shown in FIGURE l theends 7 of the outer stratum 4 are in the same transverse planes las theends 8 of the radially outer portion of the inner stratum 3. The overallshape of the sleeve 2 is conventional. A series of such sleeves aredisposed about the steel ladle stopper rod, the bottommost sleeve beingin juxtaposition to the stopper head, normally in the orientation shownin FIGURE 1, i.e., with its recess 6 disposed downwardly and itsprojection 5 disposed upwardly, although in particular cases it may beturned upside down. The sleeves may, for example, be used in a structureof the type disclosed in Patent No. 3,281,904, which structure embodiesan insert disposed in a well of the stopper head and overlying a ange atthe bottom of the stopper rod, the downward thrust of the sleeves beingtransmitted through the insert to the rod ange thereby relieving thethin upper wall portion of the stopper head of stress imposed by thesleeves when the stopper is thrust down into the ladle nozzle. Thesleeves above the bottommost sleeve are normally oriented similarly tothe bottommmost sleeve, each having the projection of the sleeve aboveor below it received in its recess. The sleeves are stacked one uponanother about the rod ange to a level above the top of the ladle sinceit is normal in open hearth practice to lill the ladle almost to ,may behighly corrosive and/or erosive and may seriously corrode and/or erodethe sleeves, particularly those sleeves at about the level of the top ofthe ladle which are subjected to the action of the slag for aconsiderably longer period of time than the sleeves below which areimmersed in molten steel. The sleeves in the region of the top of theladle are immersed in molten slag during the latter portion of thetapping of the furnace and during the time during which the ladle isbeing trans ported from the furnace to the line of ingot molds. Duringteeming the level of molten steel and slag in the ladle drops during thepouring of each ingot so that the sleeves which were initially immersedin the molten steel are subjected to the action of the corrosive and/orerosive slag for a relatively short period of time. Therefore it may bedesired in some cases to use my special sleeves in the region of the topof the ladle while using conventional sleeves therebelow.

Referring now to FIGURES 2-5, there is shown a cylindrical mold 9 openat the top and seated on an annular base 10. In FIGURES 2 and 3 a ring11 is disposed within the mold 9 and seated on the base 10. Acylindrical pug 12 of formable corrosionand/or erosion-resistantrefractory material is dropped into the mold 9 as shown in FIGURE 2. Theoutside diameter of the pug 12 is such that the pug substantially titsinto the mold 9 but with enough clearance to enable the pug to be easilyintroduced into the mold. The pug 12 seats on the ring 11 and its uppersurface is substantially at the level of the upper surface of the mold9.

A cylindrical forming mandrel 13 with a rounded nose as shown in FIGURE3 and the diameter of which is such that it fits closely within the ring11 is then moved axially downwardly through the pug 12 and thenwithdrawn upwardly, forming the pug 12 into the hollow cylinder of outerstratum 4 within the mold 9, the external diameter of the hollowcylinder 4 being equal to the internal diameter of the mold 9 and theinternal diameter of the hollow cylinder 4 being equal to the internaldiameter of the ring 11.

In FIGURE 3 the mandrel 13 is shown on its upstroke after having moveddown through the pug 12 to form the hollow cylinder 4. Some of thematerial of the pug will have been extruded downwardly and upwardlybelow and above the mold, FIGURE 3 showing the hollow cylinder 4 aftertrimming off of the extruded material. The mandrel 13 is withdrawnupwardly completely out of the mold 9 and the hollow cylinder 4 formedtherein. The hollow cylinder 4 is of corrosionand/or erosionresistantrefractory material which in the example given is a mixture ofrefractory clay and graphite.

After formation of the hollow cylinder 4 the ring 11 is replaced by aring 15 having the same outside diameter as the ring 11 and having asmaller internal diameter and being provided with an upwardly extendingexternally tapered annular projection 16 surrounding its central bore.The hollow cylinder 4 seats on the outer portion of the ring 15 with theprojection 16 extending up into the bottom of the hollow cylinder 4.

A pug 17 of formable insulating refractory material which in the examplegiven is refractory clay is dropped into the mold 9 within the hollowcylinder 4 as shown in FIGURE 4, the outside diameter of pug 17 beingsuch that it substantially ts within the hollow cylinder 4 but withsuicient clearance to allow it to be easily inserted. The pug 17 seatson the projection 16 as shown in FIG. URE 4 and its upper surface is atthe level of the upper surface of the mold 9 and the hollow cylinder 4.

A forming mandrel 18 shown in FIGURE 5 having a rounded nose and whoseoutside diameter is such that it ts closely within the ring 15 is thenforced downwardly through the pug 17 forming the pug 17 into the innerhollow cylinder of stratum 3 as shown in FIGURE 5. Some of the materialof the pug;.17 is forced downwardly outside the projection 16 to formthe recess 6 in the bottom of the stratum 3. The mandrel 18 is connectedwith a plate 20 having an annular recess 21 about the mandrel, whichrecess is of complementary shape with respect to the projection 16. Whenthe mandrel 18 and plate 20 reach their lowermost position some of thematerial of the stratum 3' is forced upwardly into the recess 21 formingthe upward externally tapered annular projection 5 on the stratum 3. Themandrel 18 is shown in FIGURE 5 as on its upstroke after having beenprojected downwardly until the plate 20 is seated atop the mold 9. Someof the materialof the pug 17 has been extruded downwardly through thecentral opening' in the ring 15. Also near the end of the downwardmovement of mandrel 18, a small amount of material from cylinder 4 hasbeen extruded outwardly between the top of the mold 9 and the plate 20as indicated by arrows 22.

Thus the stratum 3 is formed within the hollow cylinder 4 whichconstitutes the outer stratum of the sleeve. The materials of the innerand outer strata are pressed tightly together and joined and the line ofjuncture between the inner and outer strata may be somewhat irregular asshown at 19 due to the pressure imposed although when the outer hollowcylinder or stratum 4 has been formed under considerable pressure itwill substantially retain its shape while the inner stratum is beingformed within it.

Both the inner and outer strata during formation are formable, being ofthe consistency of clay. After the composite sleeve has been formed itis removed from the mold and fired in a kiln to produce the ultimatesleeve for protecting a metal stopper rod comprising a unitary hollowcylinder having an outer stratum of corrosionand/or erosion-resistantrefractory material and an inner stratum of thermal insulatingrefractory material.

While I have shown and described a present preferred embodiment of theinvention it is to be distinctly understood that the invention is notlimited thereto.

I claim:

1. A sleeve for protecting a metal stopper rod comprising a refractoryunitary hollow cylinder having an outer stratum and an inner stratum,the material of the outer stratum having a greater resistance tocorrosion and erosion than the material of the inner stratum and thematerial of the inner stratum having a greater thermal insulating effectthan the material of the outer stratum.

2. A sleeve as defined in claim 1 in which the wall thickness of theinner stratum is substantially greater than the wall thickness of theouter stratum.

3. A sleeve as claimed in claim 2 in which the wall thickness of theinner stratum is at least double the wall thickness of the outerstratum.

4. A sleeve as claimed in claim 1 in which the inner stratum is of atleast one material selected from the group consisting of zirconia,bubble alumina and refractory clay and the outer stratum is of at leastone material selected from the group consisting of al-umina, magnesia, amixture of refractory clay and graphite, Zircon and spinel.

5. A sleeve as claimed in claim 1 in which the inner stratum is of atleast one material selected from the group consisting of bubble aluminaand refractory clay and the outer stratum is of at least one materialselected from the group consisting of zirconia, alumina, magnesia, amixture of refractory clay and graphite, Zircon and spinel.

6. A sleeve as claimed in claim 1 in which the ends of the outer stratumare in the same transverse planes as the ends of the radially outerportion of the inner stratum, the sleeve having at one end an externallytapered endwise projection and at the other end a recess complementaryin shape to the projection to receive a like projection of an identicalsleeve.

References Cited UNITED STATES PATENTS 2,197,515 4/ 1940 Bruce 251-319`3,318,340 5/1967 Torti 138-140 3,379,409 4/ 1968 Fitzpatrick 251-319LOUIS K. RIMRODT, Primary Examiner U.S. C1. X.R. 251-319; 266-42

